Ashley is bracing herself for the worst summer of her life. Her best friend is moving away, and instead of being able to join her at camp for their last weeks together, Ash finds out her mom has arranged for some strange little girl to come and stay with them.

Then seven-year-old Claire shows up. Armed with a love of thrift-shop clothes and an altogether too-sunny disposition, Claire proceeds to turn Ash's carefully constructed life upside down. Besides, Ash has a secret. Ash, who is petrified of change and new people, has discovered a magical jar in her basement. It's a wish jar, filled with someone's old wishes--and it has the power to send her back in time and provide a window into another friendship between two girls. Discovering her own connection to the girls' story shows Ash that her life is full of surprises and friends she never saw coming. And while this may not be the summer that she expected, it could actually turn out to be the best summer of her life.